1. Field of the Invention
The present invention relates to a portable copier. More particularly, the invention concerns a portable copier which comprises an exposure unit and a liquid development unit, wherein these units can be employed independently from each other.
2. Description of the Prior Art
Copying apparatus or copier which has been hitherto generally employed comprises complicated optical systems and requires a great number of electrical mechanical and optical components for complicated processes and operations of the apparatus. For these reasons, attempts for miniaturizing and reducing the weight of the copier have encountered great difficulties. A copier of a portable type which can be readily transported or stored at a place of a narrow space has not been yet realized. On the contrary, hitherto known copying apparatus needs a special supporting structure, which not only makes the apparatus more bulky, complex and expensive, but also demands disadvantageously troublesome maintenance and repairs when it breaks down.
For duplicating a page of a book-like or sheet-like manuscript, and sheet originals, there have been developed copiers founded upon the dual spectrum process or the silver salt diffusion transfer technic. However, in the copier of these types, liquid developer is constantly exposed to air and likely to be easily oxidized. In reality, the use life of the developer employed in the above type copier is very short on the order of about one week.
In case of the copier constructed on the basis of the dual spectrum process, a heat-sensitive paper of a poor image density is used, which undesirably results in a degraded image quality of a poor contrast. Further, when the copier has been continuously operated, temperature within the apparatus is inevitably increased to bring about variations in the proper copying condition. Accordingly, the operator has to adjust frequently the operating conditions of the copier in consideration of the involved variations.
On the other hand, the copying method such as the silver salt diffusion transfer process in which the image of the original is printed on a photosensitive paper through a contact exposure has an advantage that it can produce a copy of a page of book-like manuscript or sheet-like manuscript. Besides, the copier using the above diffusion transfer process can be manufactured simply at a lower cost. It is, however, noted that the contact exposure apparatus based on the above transfer process has a drawback in that difficulty arises in accomplishing a perfect contact between the manuscript and the photosensitive paper, which in turn gives rise to a problem in obtaining a high quality copy having a high resolution power. When the copier is to be miniaturized, non-uniform distribution of illumination tends to occur on the exposure surface. Such being the circumstances, a miniaturized portable type copier has not yet been realized. It is further noted that a laboring procedure is required for the exchange of developer in the development apparatus of the above process type, and there is a danger that the developer should leak out of the development apparatus and adhere to the clothes and skin of the operator. Additionally, the development apparatus is difficult to be transported or carried. For these reason, it has been impractical to construct the copier of the above type in a portable size, and restrictions are imposed upon the copier having the exposure unit and a liquid development unit in respect of handling of photosensitive papers and the developer, locations at which the copier is to be used and operating conditions.